With the development of communication technology, mobile communication system has developed to System Architecture Evolution (SAE) system, and FIG. 1 is a diagram illustrating existing SAE system structure. As shown in FIG. 1, this system comprises Evolution-Ultra Terrance Radio Access Network (E-UTRAN) 101 and at least comprises core network of Mobile Management Entity (MME) 105 and Signaling Gateway (S-GW) 106, E-UTRAN 101 is used to connect User Equipment (UE) to the core network, and E-UTRAN 101 further comprises more than one macro base station (eNB) 102 and Home Base station (HeNB) 103, operational Home Base station Gateway (HeNB GW) 104, MME 105 and S-GW 106 can be integrated into one module, or be separated independently. Therein, eNB 102 are connected to one another through interface X2, and are connected to MME 105 and s-GW 106 through S1 respectively; HeNB 103 is connected to MME 105 and S-GW 106 directly, or, is connected to operational HeNB GW 104, which is connected to MME 105 and S-GW 106 through interface S1.
When a SAE system is established initially or during the SAE system operation, a large amount of human resources and material resources are required to optimize SAE system's parameters, especially wireless parameters, so as to guarantee good coverage and capacity, mobile robustness, mobile load balance of the SAE system as well as UE access speed etc. to save human resource and material resource configuration during a SAE system operation, at present, a self-optimizing method of SAE system is provided. During the self-optimizing process, eNB setting or HeNB setting is optimized according to current state of SAE system actually, and the self-optimizing method of SAE system will be illustrated hereinafter by calling eNB and HeNB as eNB uniformly.
FIG. 2 is a diagram illustrating the basic principle of self-optimizing process of a SAE system, as shown in FIG. 2, after eNB is powered on or connected to SAE, the self-optimizing process can start, and this process comprises basic configuration of eNB and initial wireless parameter configuration. Therein, basic configuration of eNB comprises configuring eNB Internet Protocol (IP) address and detecting Operation, Maintenance and Management (OA&M); authentication between eNB and core network; when eNB is HeNB, it is needed to detect which HeNB GW the HeNB belongs to; download eNB software and operation parameters to configure itself. Initial wireless parameter configuration is performed according to experience or simulation, and performance of each eNb in the SAE system will be affected by environment of the located area, so eNB has to perform initial configuration of adjacent cell lists and initial configuration of load balance according to initial wireless parameter configuration of environment of the located area. After finishing the configuration process, many parameters configured by eNB are not optimized ones, in order to provide better performance for SAE system, it is needed to optimize or adjust configuration of eNB, or called self-optimization of mobile communication system. When optimizing or adjusting the configuration of eNB, the backstage OA&M can control eNB to finish the operation, and there is a standardized interface between OA&M and eNB, OA&M sends the to-be-optimized parameters to eNB (eNB or HeNB) through this interface, and eNB optimizes the parameters configured by it according to the to-be-optimized parameters. Of course, it can also be finished by eNB itself, namely eNB detects which performances are to be optimized, and optimizes and adjusts corresponding parameters. Optimizing or adjusting configuration of eNB may comprise: self-optimization of adjacent cell list, self-optimization of coverage and capacity, self-optimization of mobile robustness, self-optimization of load balance and self-optimization of Random Access Channel (RACH) parameters, etc.
At present, basic principle of self-optimization of load balance is: neighbor cells exchange load information, when load balance is needed, the source cell can switch a UE under service to a neighbor target cell, and the target cell executes access control. When load balance is needed, the source cell can request the target cell to change switch parameter or cell reselecting parameter. The source cell notifies the target cell of relative change of cell switch trigger, and switch trigger is the special offset of a cell's triggering the switch preparing procedure. The target cell can accept the source cell's request. The source cell considers response value when executing the planned mobile parameter change.